Pump assembly composed of two pump units arranged in a casing

ABSTRACT

There is disclosed a pump assembly composed of two pump units which are separately capable of being driven and which are arranged in a casing provided with one inlet and one outlet only, said pump assembly being characterized by the intake sockets of the pump units being disposed at locations of which one is downstream of the other at a duct means coextensive from the inlet to the outlet of said casing, the pressure side of each pump unit opening into the same cut means respectively downstream of the associated intake sockets thereof, and a means being provided at the discharge of each pump unit preventing a backflow of the fluid pumped by said pump unit in said duct means.

901,450 10/1908 Keller lnventor .loclien Oplander 46 Dortmund-Horde, Nortkirchenstrasse, 100, Germany Appl No 875,639 Filed Nov. 12, 1969 Patented Aug. 31, 1971 Priority Nov. 12, 1968 Germany P 18 08 411.2

PUMP ASSEMBLY COMPOSED OF TWO PUMP UNITS ARRANGED IN A CASING 5 Claims, 2 Drawing Figs.

US. Cl 417/78, 417/426 Int. Cl F04 23/04, F04 41/06 Field of Search 417/244, 426, 78, 216, 88, 62; 415/61, 187; 417/2 References Cited UNITED STATES PATENTS 1,523,342 1/1925 Hart 417/62 2,390,161 12/1945 Mercier.. 417/88 2,813,231 11/1957 Hyde 417/2 FOREIGN PATENTS 771,837 4/1957 Great Britain 415/146 Primary Examiner-Carlton R. Croyle Assistant Examiner-R. E Gluck Anorney-Michael A. Striker ABSTRACT: There is disclosed a pump assembly composed of two pump units which are separately capable of being driven and which are arranged in a casing provided with one inlet and one outlet only, said pump assembly being characterized by the intake sockets of the pump units being disposed at locations of which one is downstream of the other at a duct means coextensive from the inletto the outlet of said casing, the pressure side of each pump unit opening into the same cut means respectively downstream of the associated intake sockets thereof, and a means being provided at the discharge of each pump unit preventing a backflow of the fluid pumped by said pump unit in said duct means.

PATENIEI] meal I97! 3.602161 1 sum 20F 2 Fig. 2

. {dig V lawn/or AL/Mp/f PUMP ASSEMBLY COMPOSED OF TWO PUMP UNITS ARRANGED IN A CASING This invention relates to a pump assembly composed of two pump units which are separately driven and which are arranged in a casing having only one inlet and only one outlet. Such a pump assembly is particularly suited for recirculating the water in heating systems.

Pump assemblies of this type are conventional in which the pump units operate individually as well as together concurrently so that they supply twice the water rating when simultaneously operating. In this regard an arrangement is conventional which includes a valve shutting a duct leading to the other pump unit when using one pump unit only and opening the ducts of both pump units when concurrently using both pump units (see German Patent 954,757).

In heating systems in residential buildings including a plurality of apartments, e.g. apartment buildings, the rating of the water to be recirculated generally extremely varies with time, and in particular the water rating to be recirculated temporarily is very low because the majority of all heating bodies has been disconnected from circulation. In this event, this results in a rise in the water pressure related to the decrease in the water rating when using water circulating pumps of the type referred to hereinbefore, and this also applies for the case that for the high rating both pump units of the assembly are permitted to operate concurrently and that for the low rating only one pump unit is permitted to operate. This rise in the water pressure is undesirable, because it can result in operating noise due to the resultant increase in the water velocity.

it is an object of this invention to eliminate this drawback. Also, the proposal of this invention to overcome this problem results in an arrangement which has further advantages regarding space requirements and machinability of the pump assembly. According to features of this invention, in a pump assembly composed of two pump units which are separately capable of being driven and which are arranged in a casing provided with one inlet and one outlet, the intake sockets of the pump units are arranged at locations of which one is downstream of the other at a duct means coextensive from the inlet to the outlet of said casing, the pressure side of each pump unit opening into said duct means respectively downstream of the associated intake sockets thereof, and a means being provided at the discharge of each pump unit preventing a backflow of the fluid pumped by said pump unit 1 in said duct means. Preferably, a closure means is provided at the discharge of each pump unit opening upon being subjected to the flow pressure of the water pumped by the pump. Also, a closure means can be provided in the duct downstream of the intake socket of each pump unit. Said closure means may comprise a flap. The means for preventing a backflow can, as an alternative, also be provided operating in the principle of a jet pump. The shafts of both pump units may be positioned on a common plane perpendicular to said duct means, a feature facilitating machining operations in the manufacture of the assembly.

With the foregoing object in view, together with such additional objects and advantages as may subsequently appear, the invention resides in the parts, and in the construction, combination and arrangements of parts disclosed, by way of example, in the following specification of certain modes of execution of the invention, reference being had to be accompanying drawings which form a part of said specification and in which drawings:

FIG. 1 is a diagrammatic sectional view of a pump assembly illustrating a first embodiment of the invention, and

FIG. 2 is a diagrammatic. sectional view of a pump assembly illustrating a second embodiment of the invention.

Referring first to FIG. 1, two centrifugal pumps 4 and the impellers of which are denominated with 4a or 5a are built into a casing 1 having an inlet 2 at one end and an outlet 3 at the other end in a manner that their shafts 4b, 5b are perpendicular to the longitudinal axis of the casing and are disposed in a common plane. The intake sockets 40, 5c of the pumps 4 and 5 open into the duct la extending straightly from the inlet 2 to the outlet 3 of the casing 1. Each pump is surrounded by a pump casing 6 or 7 disposed inside the casing 1, said pump casing 6 or 7 being closed except for an opening 8 or 9. The outlet of the pumps 4 and 5 thus opens into the interior of the casing 8 or 9. The opening 8 or 9 is capable of being closed by a flap 10 or 11 pivotable about a point of intersection 12 or 13. Two abutments 14a, 14b or 15a, 15b are provided at the casing l for each flap such that the opening 8 is closed by the flap 10 when abutting the abutment 14a, whereas it closes the duct la when abutting the abutment 14b. Similarly, the flap ll closes the duct la when abutting the abutment 15b, and it closes the opening 9 when abutting the abutment 15a. The driving motor 4d or 5d of the pumps 4 or 5 is mounted on the shafts 4b or 5b. Each of the motors can be started or stopped independently of the other motor.

The operation of this assembly is thus: when the motor 5d is operating only, thus the pump 5 is running only, the pump 5 draws water through the inlet 2 and the intake socket 5c and presses it into the interior of the pump casing 7 by means of the centrifugal impeller 5a. As a result of the water pressure obtained therein, the flap 11 is pivoted into the position in which it abuts the abutment 15b. The water pumped by the pump 5 therefore flows through the duct 1a to the outlet 3 of the casing 1. Since the pump 4 is not running, the flap I0 is pivoted into the illustrated position as a result of the water pressure existing in the duct la, the flap in this position abutting the abutment 14a. The interior of the pump casing 6 therefore is disconnected from the duct la.

If instead of the pump 5 the pump 4 is started, the position of the flaps 10 and 11 changes such that they assume the positions illustrated in phantom, i.e. such that the flap 10 abuts the abutment 14b and the flap ll abuts the abutment 15a. The pump thus draws the water through the duct la from the inlet 2 through its intake socket 4c, while the flap l0 separatesthe intake socket 4c from the outlet 3 of the casing. The flap ll disconnects the casing 7 of the inoperative pump 5.

When both pumps 4 and 5 operate at the same time, the flap 11 is brought into engagement with the abutment 15b, and the flap 10 is brought into engagement with the abutment 14b as a result of the water pressure the two flaps are subjected to. The two pumps are then operating in series. As a result thereof, the pumped amount of water is raised virtually by twice the rating. As a result of this doubling of the amount of water which is pumped, for a relatively low water throughput a rise in the pressure is obtained as long as both pumps operate concurrently. If one of the pumps is Stopped, however, as soon as the water demand drops below a predetermined limit, a water pressure is obtained which is much lower. As a result thereof, the drawbacks which result with pumps operating in parallel do not exist in the arrangement according to the invention. Since the two pump motors are located in the same plane and in the same direction as the water flows, there is a lower space requirement and a position of the pumps which is of a particular benefit for the assembly and inspection of the assembly. Also, a particularly simple machinability of the connections of the casing l for the pump motors 4d and 5d is thereby insured.

Whereas in FIG. 1 a backflow of the water pumped by one of the pumps is prevented by a flap, an arrangement is illustrated in FIG. 2 in which this is prevented by employing the principle of a jet-type pump.

Referring to FIG. 2, the formation of the casing l and the formation and arrangement of the pumps 4 and 5 together with their motors 4d, 5d and their pump casings 6 and 7 is fundamentally similar to that illustrated in FIG. 1. However, the pump casing 6 or 7 terminates in a jet-type end 16 or 17 in direction of the flow, said end being surrounded by a corresponding jet-type constriction 18 or 19 of the respective portion of the duct 1a. As a result of this arrangement, for instance if the pump 4 is running only, the water is drawn from the inlet 2 of the casing by means of the intake socket 40 through the jet-type portion 19 into the centrifugal impeller 4a of the pump 4 and pumped through the portions 16 and 18 to the outlet 3. As a result of the shape of the portions 16 and 18, a backflow from the portion 16 into the duct la is prevented. The same applies if the pump is running only. if both pumps 4 and 5 are running, they are connected in series similar to the arrangement of FIG. 1.

The pump 4 and 5 of the embodiments shown in FIG. 1 and 2 can for instance generally be permitted to run at the same time, and then one of the pumps can be stopped in the event the water demand drops below a predetermined limit. This stopping can be done either manually or automatically. If the water demand regularly drops below a predetermined rating at predetermined times, for instance at night, one of the two pumps can be stopped by means of a clock at a predetermined time of the night, and it can be started again at a predetermined time of the morning. On the other hand, the stopping and starting of the pump can be made dependent on the water quantity flowing through the pump assembly; for instance, one pump can be constantly connected with the current mains, while the other pump is connected with the current mains through a switch operated by a measuring instrument measuring the water flow through the pump assembly or measuring a pressure differential across the pump assembly.

Notwithstanding the illustrated uses of the invention and the manners by which such uses may be achieved, it is appreciated that changes and modifications will suggest themselves to others skilled in the art both for uses similar to those illustrated as well as for other uses. The invention, therefore, is not to be deemed to be limited to the exact modes of execution above disclosed by way of example, and it will be understood that the invention embraces all such changes and modifications in the parts, and in the construction, combination and arrangement of parts as shall come within the purview of the appended claims.

1. A pump assembly, comprising a casing having an inlet and an outlet and a passage connecting said inlet and said outlet for flow of fluid from the former to the latter; a pair of pump units communicating with said passage at longitudinally spaced portions thereof, each of said pump units having an intake opening and a discharge opening of which the latter communicates with said passage downstream of the former; and closure means in the region of said discharge opening of each of said pump units for preventing the backflow of fluid discharged from the respective discharge opening, said closure means comprising respective flaps each mounted for movement under the influence of fluid pumped by the associated pumping unit from one terminal position blocking the respective discharge opening to an other terminal position unblocking such discharge opening and blocking said passage intermediate the respective discharge opening and the associated intake opening.

2. A pump assembly, comprising a casing having an inlet and an outlet, and a passage connecting said inlet and said outlet for flow of fluid from the former to the latter; a pair of pump units communicating with said passage at longitudinally spaced portions thereof, each of said pump units having an intake opening and a discharge opening of which the latter communicates with said passage downstream of the former; and closure means in the region of said discharge opening of each of said pump units for preventing the backflow of fluid discharged from the respective discharge opening said closure means comprising respective flaps each associated with one of said pump units and mounted downstream of said intake opening thereof for movement between one terminal position blocking the associated discharge opening and an other terminal position unblocking such discharge opening and blocking said passage.

3. A pump assembly, comprising a casing having an inlet and an outlet, and a passage connecting said inlet with said outlet for flow of fluid from the former to the latter, a pair of pump units communicating with said passage at longitudinally spaced portions thereof, each of said pump units having an intake opening and a discharge opening of which the latter communicates with said passage downstream of the former; and

respective means, operative in the manner of a jet pump and each having a nozzle portion receiving fluid from a respective discharge opening for discharging such fluid along and in downstream direction of said passage and a flow-constricting portion surrounding the nozzle portion, for preventing a backflow of fluid pumped by the respective pump units.

4. A pump assembly as defined in claim 2, said pump units each having a drive shaft, and wherein said drive shafts are located in a plane common to them both.

5. A pump assembly as defined in claim 2, said pump units each having a drive shaft which extends normal to the elongation of said passage. 

1. A pump assembly, compriSing a casing having an inlet and an outlet and a passage connecting said inlet and said outlet for flow of fluid from the former to the latter; a pair of pump units communicating with said passage at longitudinally spaced portions thereof, each of said pump units having an intake opening and a discharge opening of which the latter communicates with said passage downstream of the former; and closure means in the region of said discharge opening of each of said pump units for preventing the backflow of fluid discharged from the respective discharge opening, said closure means comprising respective flaps each mounted for movement under the influence of fluid pumped by the associated pumping unit from one terminal position blocking the respective discharge opening to an other terminal position unblocking such discharge opening and blocking said passage intermediate the respective discharge opening and the associated intake opening.
 2. A pump assembly, comprising a casing having an inlet and an outlet, and a passage connecting said inlet and said outlet for flow of fluid from the former to the latter; a pair of pump units communicating with said passage at longitudinally spaced portions thereof, each of said pump units having an intake opening and a discharge opening of which the latter communicates with said passage downstream of the former; and closure means in the region of said discharge opening of each of said pump units for preventing the backflow of fluid discharged from the respective discharge opening said closure means comprising respective flaps each associated with one of said pump units and mounted downstream of said intake opening thereof for movement between one terminal position blocking the associated discharge opening and an other terminal position unblocking such discharge opening and blocking said passage.
 3. A pump assembly, comprising a casing having an inlet and an outlet, and a passage connecting said inlet with said outlet for flow of fluid from the former to the latter, a pair of pump units communicating with said passage at longitudinally spaced portions thereof, each of said pump units having an intake opening and a discharge opening of which the latter communicates with said passage downstream of the former; and respective means, operative in the manner of a jet pump and each having a nozzle portion receiving fluid from a respective discharge opening for discharging such fluid along and in downstream direction of said passage and a flow-constricting portion surrounding the nozzle portion, for preventing a backflow of fluid pumped by the respective pump units.
 4. A pump assembly as defined in claim 2, said pump units each having a drive shaft, and wherein said drive shafts are located in a plane common to them both.
 5. A pump assembly as defined in claim 2, said pump units each having a drive shaft which extends normal to the elongation of said passage. 